Diabetes has been known to affect other parts of the body such as kidney and heart. There have been conflicting reports about the association of diabetes with the lung function.

A meta-analysis of 40 studies was carried out wherein the lung function data of around 3,200 diabetics and around 27,100 controls was studied. The lung function parameters analyzed included FEV 1 , FVC, FEV 1 /FVC ratio and DLco from studies published between the years 1966 to 2009.

With regards to the FEV 1 /FVC ratio, the 0.1% mean difference was not significant (95% CI, - 0.8 to 1.0, p =0.78).

The BMI, smoking, diabetes duration, or glycated hemoglobin were not found to significantly contribute to the between-study heterogeneity as analyzed by meta-regression analysis (all p > 0.05).

The authors found a slight but statistically significant, impairment in the pulmonary function with the presence of diabetes. Type II diabetes was found to have a stronger association compared to type I diabetes.

Further studies in diabetic patients with pulmonary disease such as asthma and COPD are suggested.

CHEST 2010; 138(2):393–406

Asthma morbidity is largely associated with asthma exacerbations which are most often due to respiratory tract infections. Exacerbations also contribute considerably to burden of asthma. It has been thought that vitamin D may have a role in prevention of asthma exacerbations.

The Childhood Asthma Management Program was a multicentric, randomized, double-blind, placebo controlled trial. The children were randomized to receive budesonide, nedocromil, or placebo (as-needed ß 2 -agonists) for the study period of 4 years. It evaluated vitamin D (25-hydroxyvitamin D levels) in serum and successive severe exacerbations of asthma in more than thousand children with mild-to-moderate persistent asthma at the time of enrollment.

The relationship between baseline vitamin D levels and the risk of any hospitalization/emergency department visit over the trial was evaluated using statistical analysis. Vitamin D insufficiency was reported when the serum levels of 25-hydroxyvitamin D were 30 ng/mL or less.

Vitamin D insufficiency was seen in 35% of subjects. The highest mean vitamin D levels were seen in whites whereas lower values were recorded in African Americans. There were higher odds of a hospitalization or emergency department visit with vitamin D insufficiency after excluding age, sex, BMI, income and treatment group (adjusted odds ratio for insufficient vitamin D status: 1.5; 95% CI, 1.1-1.9; p = 0.01).

Insufficient vitamin D status was commonly seen in North American children with mild-to-moderate persistent asthma. Vitamin D insufficiency was linked with higher odds of severe exacerbation over the 4-year duration of the study.

J Allergy Clin Immunol 2010; 126:52-8.

Studies in the past have reported on the association of wood smoke exposure with increased respiratory symptoms and illnesses. The current study analyzed the association of wood smoke exposure with chronic obstructive pulmonary disease COPD and smoking.

The study evaluated 1861 COPD individuals (mostly females) out of which 1079 were current smokers and the remaining had quit smoking. The study population was based in Southwestern United States

A 96% increase in the risk of airflow obstruction and an approximately 65% increase in the risk of chronic bronchitis was seen with exposure to wood smoke. Risk was even more amongst individuals who were current smokers. There was a 2.71-fold increased risk of airflow obstruction and a 5.74-fold increased risk of chronic bronchitis for combined wood and cigarette smoke exposure. Other factors associated with an increased risk of COPD amongst individuals with wood smoke exposure included a combination of Hispanic ethnicity and male sex.

Methylation of genes (p15 or GATA4) in sputum in addition to wood smoke exposure also increased the risk of COPD. There was a decrease in the percent predicted FEV 1 along with airflow obstruction with a high methylation index i.e. when 2 or more genes were methylated compared to a low methylation index.

Authors concluded that individuals who smoked tobacco should prevent wood smoke exposure as it was associated with a higher risk for COPD.

Am J Resp Crit Care Med 2010

There is a paucity of information on the path of mild to moderate persistent asthma in children. The study was taken up to understand the path of asthma in childhood and predictors of various categories of asthma (remitting, periodic, and persistent asthma).

The Childhood Asthma Management Program was a randomized, double-masked study and was carried in multiple centers. It evaluated 909 children with mild to moderate persistent asthma for a period of over 4 years wherein the patients were randomized to receive continuous therapy with either budesonide or nedocromil, each versus placebo. This treatment period was followed by a 4-year observational follow-up period.

Children were said to have remitting asthma (no asthma activity in the last year), persistent asthma (asthma activity in every 3 months) or periodic asthma (neither remitting nor persistent). A child was said to have asthma activity if there was contact with local medical provider, leave from school, visits to the emergency department (ED), and hospitalization as a result of asthma; wheezing or any other exercise-induced symptoms; or use of relievers or controllers.

55% of children had persistent asthma, 39% had periodic asthma and remaining had remitting asthma. The airway hyperresponsiveness, eosinophilia and asthma morbidity were found to improve over the study period in all the 3 categories of asthma.

Children with remitting asthma were at higher odds of lacking allergen sensitization as well as exposure to indoor allergens, milder asthma, older age, low airway hyper-responsiveness, higher pre-bronchodilator FEV 1 % predicted, lower FVC% percent predicted at baseline compared against those having persistent asthma (all p values being significant).

Childhood asthma remission is uncommon and unaffected by 4 years of anti-inflammatory controller therapy. Remission gets affected by presence of allergen sensitization and exposure, low lung function and airway greater hyper-responsiveness.

J Allergy Clin Immunol 2010;125: 359-66.